Low- and high-grade esthesioneuroblastomas display a distinct natural history and outcome

Purpose: Esthesioneuroblastomas, also called olfactory neuroblastomas (ENB) represent a rare sinonasal neurectodermal tumour which prognostic factors are unsteadily described. Patients and methods: Clinical and pathological characteristics were analysed in patients treated at Gustave Roussy Institute between 1979 and 2009. Results: Out of 63 patients, 19 patients were reclassified and 44 patients were eligible for the analysis. Multivariate analysis revealed that T staging of the modified Dulguerov TNM staging and Hyams grade > III (that we termed high-grade ENB) were the only independent prognostic factors for overall survival (OS). As compared to patients with low-grade ENB (Hyams grade ≤ III), patients with high-grade ENB have higher T4 staging (p = 0.02), have frequent lymph node involvement (p = 0.009) and are more often unresectable (p = 0.005). Resected patients with high-grade ENB frequently displayed mainly leptomeningeal metastasis (n = 4/6) in contrast to patients with low-grade ENB who typically experience late loco-regional recurrence (n = 10/25). With a median follow-up of 9.6 years, median DFS and OS for resected low-grade ENB were 5.4 and 20.5 years, respectively. Conversely, median DFS and OS for high-grade ENB were 1.5 and 2.5 years, respectively. Conclusion: Low and high-grade ENB display distinct patterns at presentation and relapse, leading to different prognosis. Therefore, they may be regarded as distinct entities.